Insulator.



F. SIEBER.

INSULATOR.

APPLICATION mw JuLY 15. 1914.

Patented Jan. 15, 1918.

554215Z .0L- @w @2% UNITED sTATEs PATENT oEEICE.

'FERDINAND SIEBER, or CHAELOTTENEURG, GERMANY,v AssIGNoE To GENERAL ELECTRIC COMPANY, A CoEPoEATIoN or NEW YCEK.

IN SULATOR.

To all whom it may concern:

Be it known that I, FERDINAND SIEBER, a subject of the Emperor of Austria, residing at Charlottenburg, Germany, have invented certain new and useful Improvements in Insulators, of which the following is a specification.

My invention relates to insulators, and more particularly to the insulation 0f conductors where they pass through conductive parts or structures of electrical potentials different from their own. My invention is especially applicable to sleeve insulators for transformer leads carrying currents at very high voltages,-such .as 100,000 to 150,000 volts, for example-and in explaining the invention hereinafter and describing the best embodiment at present known to me, I have therefore referred especially to this use of it. While, however, the invention extends to various specific features and details and combinations and arrangements of parts hereinafter illustrated and described, it is not confined thereto, but can be otherwise carried out and applied. Various advantages obtainable in connection with the invention will appear hereinafter and its scope will be indicated in my claims.

In the case of an-insulator for; the passage of a conductor through the wall structure of a transformer casing or the like, the greatest difference of potential occurs at the opposite sides of the casing wall, so that the danger of creepage or other trouble is great- Vest there. In'accordance with my invention,

I improve the electricalfvconditions by arranglng between the casing (or other external metal layer) and the current carryin conductor a conductive protecting shiel consisting of a layer of conducting material with insulating material pressed all about it or otherwise embedding it,-'-especially a`t the outer edges,-this shield being electrically connected with the transformer casing (or other external layer) and laterally eX- tending the surface to which it is electrically connected beneath the surface of the insulating material. The distance from the protective shield to the exposed portion of the conductor beyond the insulating material is therefore less than the distance of the Casin wall therefrom, and the dierence o f potentlal per unit length along the out- Slde surface of the insulator adjacent the Specification of Letters Patent. Patented Jan. 15, 1918.

Application led July 15, 1914. Serial No. 851,193.

casing wall, and consequently the danger of creepage, is thereby considerably reduced. The shield means may consist of annular members embedded in a mass of insulation and conductively connected together, or may be made by embedding in a mass of insulation a sheet metal cylinder whose edges will preferably have been thickened to prevent excessive density of the electrostatic lines of force at these extremely dangerous places. It is advantageous to arrange the protective shield means in the walls of the insulator itse1f,-or, if the insulator is built up in a plurality of parts, in one of the insulating parts. In any case, the density of theI electrostatic lines of force will be greatest at the opposite sides of the -protective shield where the insulation is good.

The accompanying drawing shows a construction embodying the invention that is suitable for a high voltage transformer lead, most of the parts being in section. Here a sort of flanged'collar or holder 1 for receiving the insulator is secured to the ca sing wall 2. The sleeve insulator proper 1s built -up of three parts: the two end pieces 3, 4 and the middle piece 5 interposed between the collar 1 and the conductor or lead proper. In the middle part 5 is embedded a sheet metal cylinder 7 with its edges 8, 8 thickened and rounded, and this metal cylinder 7 is conductively connected to holder o r collar 2 by means of a flanged collar-like metal piece 9 that rests on or is secured to it. Here the thickened edges 8, 8 are 1n effect the conductively connected annular members already mentioned. The interior of the whole insulator will preferably be filled with oil or other insulating fluid.

What I claim as new and desire to secure by Letters Patent of the United States, 1s

1. An insulator for the passage of a conductor through a conductive structure cornprising a sleeve of insulating material and a conductive shield about the conductor where it passes through said structure completely embedded in the wall of said sleeve and electrically connected to said structure.

2. An insulator for the passage of a conductor through a conductive structure comprising a sleeve of insulating material and a conductive shield about the conductor where it passes through said structure com prising separated annular parts electrlcally i sleeve.

.connected together and to said structure and completely embedded the wall of said 3'. An insulator for the passage of a conductor through aconduetive structure comprising la sleeve of insulating material and a conductive shield about the conductor whereit passes through said structure consistirg` of separated annular parts` forming the thickened edges of a sheet metal cylinder interposed between said conductor and said structure, said shield being electrically connected to said structure and being comexternal metal layer and being electrically connected with said external metallayer.

5. The combination with a conductor, a

conducting member surrounding the same, and insulating materiall between said conductor and said member for insulating vthe Same fom each (athen-fofmeans for suppressing brush discharge'grom said, conducting member comprisinga layer., of conducting material surrounding said. 'c'nductoly embedded in said insulating material, laterally extendingthe surface of said conducting member which is toward said conductor,

and electrically connected to said conducting member.

6. The combination with a conductor, an-V' other conductor adj acent'the rst mentioned conductor, and insulating material between said conductors for insulating the same from each other, of means for suppressing brush ydischarge'from one of said conductors adjacent the. surface of said insulating material,

said means comprising alayer of conducting rial and 4electrically connected to said last mentioned conductor and enlarging the lat eral extension of the surface of the samebeneath the surface of the insulating material.

In witness whereof, 'I have hereunto setv my hand this 17th day of June, 1914.

. FERDINAND SIEBER.

Witnesses l WOLDEMAR HAM, HENRY HAsPER.'

4'5 v material, embedded in said insulating mate- 

